Faculty of Science and Technology, Queensland University of Technology, GPO Box 2434, Brisbane, Qld 4001, Australia.
Phys Med Biol. 2010 Nov 21;55(22):N533-45. doi: 10.1088/0031-9155/55/22/N02. Epub 2010 Oct 28.
In this study, the feasibility of difference imaging for improving the contrast of electronic portal imaging device (EPID) images is investigated. The difference imaging technique consists of the acquisition of two EPID images (with and without the placement of an additional layer of attenuating medium on the surface of the EPID) and the subtraction of one of these images from the other. The resulting difference image shows improved contrast, compared to a standard EPID image, since it is generated by lower-energy photons. Results of this study show that, firstly, this method can produce images exhibiting greater contrast than is seen in standard megavoltage EPID images and secondly, the optimal thickness of attenuating material for producing a maximum contrast enhancement may vary with phantom thickness and composition. Further studies of the possibilities and limitations of the difference imaging technique, and the physics behind it, are therefore recommended.
在这项研究中，探讨了差分成象技术提高电子射野影像装置（EPID）图像对比度的可行性。差分成象技术包括采集两张 EPID 图像（一张有附加的衰减介质层，另一张没有），然后从其中一张减去另一张。与标准 EPID 图像相比，生成的差分图像对比度提高，因为它是由低能光子产生的。这项研究的结果表明，首先，这种方法可以产生比标准兆伏 EPID 图像对比度更高的图像，其次，产生最大对比度增强的最佳衰减材料厚度可能随体模厚度和组成而变化。因此，建议进一步研究差分成象技术的可能性和局限性及其背后的物理原理。
